I worked at J.P. Morgan, then McKinsey and have just started my own business. This is what I've learned

I delivered eight venti unsweetened green iced teas, hold the ice, twice per day. This order fueled the Lehman Brothers credit default swap trading desk in August 2008, and placing it was one of my chief responsibilities as a summer intern. I had a front-row seat for the meltdown forever marked by the firm declaring bankruptcy the following month. Welcome to Wall Street.

How did I go from Wall Street intern and later analyst promoted to associate at J.P. Morgan to associate at McKinsey & Co. and then finally to founder and CEO of my own startup, all before age 30?

1. Confidence

Mastering food and coffee orders is a rite of passage for interns and new analysts across Wall Street. It’s a test for two of the key qualities necessary to survive as a junior trader: attention to detail and humility. I’d later learn that to thrive as a trader – as well as an entrepreneur – those qualities must be mitigated with a hefty dose of confidence.

After my stint at Lehman Brothers, I joined J.P. Morgan as a summer intern on the oil derivatives trading desk, where I later worked full-time as an analyst.

The best traders I worked for at J.P. Morgan were the most proactive. They offered quotes for option prices – unprompted – to search for opportunities or possible pricing inefficiencies versus waiting for customer flow to drive activity. I took the same approach to getting my own trading book after I had survived that first wild year on the desk.

I asked the trader who liked me the most whether I could trade in very small amounts inside his personal portfolio. It was a proof-of-concept or a “minimum viable product,” to borrow language from the world of startups, that helped build his trust in my abilities and allowed me the confidence necessary to justify getting my own risk book, which led to a promotion to associate later that year.

2. Creativity

When I decided to leave trading for a less-specialized path in generalist management consulting at McKinsey, it was important to me that I join the consulting firm as an associate. I wasn’t comfortable with a demotion in title, even though I was changing industries. However, there was no precedent for doing so without a graduate degree.

I applied as an analyst. After receiving an offer, I successfully negotiated my title and salary to associate. After all, “no” is just a starting point for creative negotiation.

3. Challenge

When I was at Mckinsey, I launched an event production company as a “side hustle.” As it began to be successful, I got a taste of entrepreneurship. Every day, I woke up with new business concepts on the brain – all of which relied on technology to achieve scale – but I didn’t know how to code and couldn’t build products on my own.

Instead of seeing my lack of experience as an obstacle, I accepted the challenge to cultivate my skillset: I enrolled in a full-time, four-month web development course at General Assembly. At the end of the course, I was confident in my ability to create the tools necessary to set my ideas in motion.

4. Coaching

Throughout my career, I've had challenges such as stress management at work, transitioning to new roles, salary and benefits negotiation, and major industry changes. But founding your own startup is another thing altogether.

When I left McKinsey to start my own business, I knew I needed some guidance. I began to surround myself with startup founders who had a passion and appetite for risk. Through a friend’s referral, I met my career coach. I quickly realized the benefits of having an unbiased, trained expert to clarify my goals, improve my confidence and, later, to navigate the earliest days of launching a startup.

The world of work is changing at a more rapid pace than in any past period and the most successful professionals will increasingly be the most versatile. I see coaching as the best mental-training tool to propel the modern workforce forward to the future.

Anastasia Alt is the founder of Dream Space, a career education, support and advisory service via text messaging and video, and a former associate at both J.P. Morgan and McKinsey & Co.